ActiveMQ - What happens to unsent messages in a topic?

[Timothy Sam]

Topic = Multiple subscribers
Queue = One consumer, deletes the messages once sent?

So, say I have 3 consumers in a topic.

1. If only one of them is able to receive the message, is the message queue and waits for the other two consumers to consume it?
2. What happens once all consumers in a topic consumes a message? Is the message deleted?

Thanks!